Due to a limited spectrum utilization rate in wireless cellular communications systems, bandwidth occupied by each user is limited, presenting an increasing challenge to meet transmission requirements of high-speed data services. Consequently, an urgent need exists for an approach to provide users with more reliable high-speed data services in wireless broadband mobile networks.
To increase the spectrum utilization rate, the CA (Carrier Aggregation, carrier aggregation) technology is introduced in LTE-A (Long Term Evolution Advanced, Long Term Evolution Advanced). The CA technology utilizes spectrum resources scattered in multiple bands to acquire a wider bandwidth, thereby increasing a peak data rate and a system scheduling rate, and addressing the problem of an operator's spectrum bands being non-contiguous.
Data to be received by a multi-carrier terminal (a terminal using the CA technology, namely, a terminal for which multiple carriers are activated) is received over an air interface of each carrier. A scheme used by the multi-carrier terminal to receive data is as follows: After receiving data from an air interface of each carrier, the multi-carrier terminal assembles the received data into complete final data and then transfers the complete final data to an upper layer of the multi-carrier terminal for use. It is a key technical challenge to obtain an optimal scheduling rate and optimal fairness while maximizing a utilization rate of spectrum resources during data transmission over multiple carriers.
The PF (Proportional Fair, proportional fair) scheduling policy is typically used by data services in wireless communications systems. A basic philosophy of the PF policy is to try to maintain a balance between scheduling rate and fairness. When the carrier aggregation technology is in use, each multi-carrier terminal can send/receive data over multiple component carriers (Component Carrier, CC). However, which carrier is used by a user to send/receive data is transparent to an RLC (Radio Link Control, radio link control) layer.